MySQL: Add xbstream unarchiver to wal-g

[ostinru]

Add xbstream unarchiver to wal-g, so we can eliminate xbstream --extract from backup-fetch pipeline and do it on our own.

Note 1: current PR doesn't embed new unarchiver to backup-fetch pipeline.

[ostinru]

For backup that is 123M (zstd compressed) I got exact matching with xbstream:

WAL-G:

WALG_LOG_LEVEL=DEVEL ./main/mysql/wal-g xb extract ~/development/incremental/bk.xb ~/development/incremental/bk/ --decompress
ostinru@ostinru-MBP ~/development/incremental $ find bk -type f | sort -u | xargs cat | md5sum
3ba456093aee2bba2e11b119a47131ec  -

XBSTREAM:

ostinru@ostinru-MBP ~/development/incremental $ cat bk.xb |  xbstream -x -C bk --decompress
ostinru@ostinru-MBP ~/development/incremental $ find bk -type f | sort -u | xargs cat | md5sum
3ba456093aee2bba2e11b119a47131ec  -

And same results without decompress:
WAL-G:

WALG_LOG_LEVEL=DEVEL ./main/mysql/wal-g xb extract ~/development/incremental/bk.xb ~/development/incremental/bk/
ostinru@ostinru-MBP ~/development/incremental $ find bk -type f | sort -u | xargs cat | md5sum
3cb96984d1202d7c7db059aa546738fd  -

XBSTREAM:

ostinru@ostinru-MBP ~/development/incremental $ cat bk.xb |  xbstream -x -C bk
ostinru@ostinru-MBP ~/development/incremental $ find bk -type f | sort -u | xargs cat | md5sum
3cb96984d1202d7c7db059aa546738fd  -